Carburetor for internal combustion engines



Sept. 20, 1938. E. T. BUNT 2,130,337

CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 5, 1935 2 Sheets-Sheet l f f f z f W1 5 2 A 0 l 3 9 I: q 12 57" g J 0g I 27 "E? q a INVENTOR EDWARD TREZISE BUNT ,Q ATTORNEYS Sept. 20, 1938. E. T. BUNT 2,130,337

CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 5, 1935 2 Sheets-Sheet 2 g 1 0 WJZ INVENTORI EDWARD TREZISE. BUNT ATITORNEA/S Patented Sept. 20, 1938 UNITED STATES PATENT oFFieE CARBURETOR FOR INTERNAL COMBUSTION ENGINES Bristol, England Application August 5, 1935, Serial No. 34,768 In Great Britain August 11, 1934 2 Claims.

This invention relates to carburetors for internal combustion engines, its chief object being to promote the atomization and vaporization of the fuel (petrol, oil, parafiin, or the like), and a subsidiary object being to enable the carburetor to act as an automatic supercharger in motor vehicles.

In order that the said invention may be clearly understood and readily carried into effect, the same will now be described with reference to the accompanying drawings illustrating exemplifications of the invention.

Figure 1 is a side elevation of a carburetor.

Figure 2 is an elevation of the other side of the same carburetor with the cowl and front portion both removed.

Figure 3 is a rear view.

Figure 4 is a front view of the rear portion. of the carburetor with a transverse rotatable gauze screen in position.

Figure 5 represents gauze screens of modified form alternating with vanes or propeller blades tobe located on a pin extending longitudinally of the expansion chamber.

Figure 6 is an underside View illustrating alternative means for moving the outer perforated tapered ring.

Figure 7 represents in side elevation a modification in which the movable perforated member is a cup inside the relatively fixed member.

Figure 8 represents a longitudinal section through the carburetor shown in Figure 7 taken on the line 8-8.

Figures 9 and 10 represent alternative modified means for controlling the fuel supply.

Figure 11 is an end elevation and Figure 12 a vertical section of a plug representing a further modification.

A indicates the front cup or portion of an expansion chamber which is a bulb and may be spherical or as shown of somewhat elongated form, that is, approximately oval, and preferably made in two separate halves or portions for convenience in assembling or dismantling the apparatus, having a. tubular extension a for connection to the engine manifold. B indicates the rear cup of the expansion chamber, and C a rearward cylindrical extension thereof which may be called the choke tube, strengthened by a ring 11 and provided with an inlet pipe D into which can be inserted a fuel jet (not shown) connected with an ordinary or other float chamber. A substantially hemispherical cowl E is secured in any suitable manner outside the cylindrical portion C with its concave side forwardly directed,

and may if necessary be recessed at one side to enable the float chamber to be placed in juxtaposition tothe said portion C, the cowl being in practice in a position overlapping the expansion chamber, that is, further forward than the position in which it is shown for the sake of clearness. The cowl is located at the rear of the expansion chamber and over the carburetor to receive hot air from the vicinity of the fins of the radiator in a motor Vehicle and deliver it to the carburetor, so that whilst avoiding the eifect of back draught due to the speed of the vehicle, the velocity of the air stream supplied to the carburetor increases as the speed of the vehicle increases, and the flow of fuel is also increased, so that the device is not merely an extra air device, but operates as an automatic supercharger. 7

Referring to Figures 1 to 4, the meeting faces of the cup-shaped members A and B are screwthreaded to facilitate assembly and dismantling. A tapering or conical rear portion of the cup B is perforated with three rows or rings of radially directed holes of equal or graduated sizes and outside this portion is a tapered or conical ring F circumferentially movable in relation to the cup B and perforated with corresponding rows of holes f f i The holes of the rear-most row f are preferably of larger diameter than those of the other two rows. By graduated angular, that is, arcuate movements of the ring F air can be admitted to the chamber through one, two,- or all of the rows of perforations in the shell. The arcuate movements of the ring F may be effected by a convenient controlling means, but an example of a possible hand control is given. A screw G having a milled head 9 works in a screw threaded bearing H secured on the cup B, and its extremity is rotatably secured in a bearing 9 on the ring F (see especially Figures 2 and 8) a spring 9' in compression surrounding the shank of the screw G between the two bearings H and 9 Alternatively, as seen in Figure 6 the smaller .end of the ring F may have two recesses or notches in which stops J engage, a spring K in tension being anchored to the ring F and cup B and tending to hold the ring F in the position relatively to the cup in which the perforations in the ring are not in register with those in the cup, an arm M on the ring adapted to be set by any suitable controls placing the respective perforations in register to the desired extent. If the air inlets are entirely closed then liquid fuel is drawn into the expansion chamber by suction. A rotatable rod P terminating in a milled head P passes through the centre of the extension C and carries at its front end a disc in which are a number of perforations adapted to be brought into register with similar perforations Q (see Figure 4) in a relatively fixed disc adjacent the base of the cup B. A fan or screen of wire gauze consisting of four wings (only two of which R and R are shown) directed 90 degrees apart from each other and secured on a. spindle r may be mounted in bearings r in the cup B in such manner as to be capable of rotating freely in an inclined plane or in a horizontal or in a vertical plane according to the positions of the bearings. Alternatively a spindle 1' may be fitted into a hole in the centre of the base of the cup B to occupy a longitudinal position in an expansion chamber formed by the cups A and B, and on this spindle are placed a series of transverse wire gauze discs or screens T intermediate of which are rings of vanes or propeller blades S, mounted on the spindle r in a freely rotatable manner, the screens being also rotatably mounted if desired. The screens are especially useful in dealing with fuel of poor quality. The screens can be varied in number and texture according to the grade of fuel used.

Referring now to Figures '7 and 8, in this embodiment a perforated inner shell or cup T is movable in a relatively fixed perforated outer cup B. The petrol jet D enters a hole D bored through the parts B and C. The fuel passes through one of a number of perforations in a disc 11 on the front end of the rotatable rod or spindle P, and through a perforation Q (Figure 8) in the end of the choke tube cylinder C. A series of disc screens r may be placed within the expansion chamber on a spindle 1' which is pivoted on a rod r passing through the cup T. The rod r is circumferentially movable in relation to the outer shell B, as it works in slots r atopposite sides of the shell B, these slots being circumferentially directed in the shell B to allow such movement of the rod T and as the said rod is rigidly connected with the inner shell T, relative rotary movement can be given to the shell T within the shell B. Both the shell B and the shell T are perforated with rings of holes f, f f*, of varying numbers, sizes, and spacing, and by relative rotation a greater or less number of holes in the different rings in the shell T can be brought into register with the corresponding holes in the shell B, and thus the total area available for the admission of air to the expansion chamber within the shell T can be regulated. The rod 1' may be provided with washers, collars, or anti-friction bowls T", r to facilitate its smooth working, and a spring r may be compressed against the washer r to prevent slackness.

The control of the admission of the fuel to the expansion chamber may be effected by means of a slide having a rectilinear movement instead of by a rotary disc as already described. The slide W, Figure 9, is suitably guided across the forward end of the. choke tube or extension C, a wire Z011 being provided to lift the slide against the resistance of a spring 20 in a casing at the top of the slide, and a suitable stop being provided to limit its downward movement under the impulse of the spring when released. The slide has holes or ports to and w of different sizes. The larger hole is gradually closed off from the choke tube or expansion C by the movement of the slide before the smaller one comes into operation.

Figure 10 illustrates in vertical central section another modification in which the control of the admission ,of fuel is effected by means of a rod Y arranged transversely in the choke tube C and passing through a bushing c in the said tube, this rod having a perforation which in the position shown coincides with the bore of the bushing. The rod Y can be rotated by any convenient external means to close the bore wholly or partly. The rear end of the tube is closed by a screw cap 0 The alternative choke tube C illustrated in Figures 11 and 12 is a cylindrical plug having a screw threaded inlet D for the attachment of a pipe (not shown) for conveying liquid fuel from a float chamber or other source of supply, this inlet D communicating with an eccentric bore 0 in which is a roll of wire gauze 0 The opening of the bore 0 towards the expansion chamber is covered by an approximately semi-circular plate Z. The fuel is drawn by the engine suction through the bore 0 and creeps under the plate Z, being then drawn in a finely atomized state into the expansion chamber.

It will thus be seen that a carburetor according to the invention comprises an expansion chamber between the fuel jet and the engine, means permitting fuel to be drawn at a considerable pressure and speed through an aperture or apertures and instantly released in a vaporized or finely, divided form into the relatively large space within the expansion chamber at a low pressure, and means toadmit into said chamber a relatively large quantity of air directly from the atmosphere in separate streams radially directed through a large number of circumferential openings to impinge transversely on the stream of fuel, whereby the diffusion of the fuel is improved and a more perfect combustion obtained, whereby economy in the consumption of fuel results with greater power.

Having now fully described my invention, I claim:

1. In a carburetor for an internal combustion engine to be used on a vehicle, an elongated expansion chamber connected to the engine and open to engine suction, means for delivering a regulated stream of liquid-fuel into said chamber, the shell of said chamber having a large number of relatively small circumferential openings located between the engine and the point of entry of the fuel, said openings serving to admit directly from the atmosphere to said chamber all of the air required for admixture with the fuel in the form of separate streams impinging transversely on the stream of fuel being delivered, in combination with a cowl placed behind the fuel and air admission devices with its concave side facing in the direction of travel of the vehicle, for the purpose of receiving heated air from the radiator of the vehicle and directing said heated air to the carburetor.

2. In a carburetor for an internal combustion engine, in combination an expansion chamber connected to the engine and open to engine suction, exterior means for delivering a regulated stream of finely diffused liquid fuel into said chamber, the shell of said chamber having a large number of relatively small circumferential openings of rings and arranged in a plurality located between the engine and the point of entry of the fuel, said expansion chamber also being located between the engine and the point of entry of the fuel and said openings serving to admit directly from the atmosphere to said chamber all of the air required for admixture with the fuel in the form of separate streams impinging transversely on the stream of fuel being delivered, and control means being provided between the engine and the point of entry of the fuel for controlling said circumferential openings including an angularly movable control ring member having perforations adapted to register with said openings, said perforations being so arranged that by graduated angular movements of said ring member one or more of said rings of openings can be closed to reduce the rate of admission of air to the interior of said 

